This invention relates to flow control, and, more particularly, to the control of fluid flow making use of pressure differentials.
In many situations it is necessary to control the flow of fluids, such as liquids and gases. A common device for that purpose is known as a check valve. It functions by the deflection of an elastomeric element towards a valve seat in order to prevent flow and away from the seat to permit flow.
One such device is the check valve disclosed in U.S. Pat. No. 3,889,710 which issued to Julien H. Brost on June 17, 1975. It contains an elastomeric disc that is deflected towards and away from a concave seating surface that surrounds an inlet. The disc is deliberately made smaller than the seating surface. This is to permit reverse flow around the edges of the disc.
Unfortunately, the use of a concave seating surface with a floatable disc, i.e. one that is smaller than the seating surface, causes a number of difficulties. In the first place a valve with a concave seating surface is susceptible to malfunction because inevitable particles of debris that become trapped between the disc and its concave seat. Once debris becomes trapped it tends to remain on the seat during subsequent operations of the valve. In addition since the disc is smaller than its seat it tends to move about with the result that different portions of the surface become stressed during subsequent operations. Furthermore, there is an undesirable tendency for a portion of the disc to be drawn into the associated inlet during closure operation of the valve.
Other known valves for controlling flow are those illustrated by the following patents:
______________________________________ Patent No. Issued Inventor ______________________________________ 797,739 8/1905 Meer 1,412,473 4/1922 Lane 1,506,012 8/1924 Lewis 2,547,377 4/1951 Juhasz 3,342,866 4/1966 Sanz 3,664,371 5/1972 Schneider ______________________________________
Still other known valves for controlling flow are those illustrated by the following additional patents:
______________________________________ Patent No. Issued Inventor ______________________________________ 3,807,445 4/1974 McPhee 3,954,121 5/1976 Kardos ______________________________________
Accordingly, it is an object of the invention to facilitate the control of fluid flow. A related object is to facilitate the control of fluid flow using differential pressures.
A further object of the invention is to overcome the difficulties associated with prior check valves. A related object is to avoid the difficulties associated with a single disc check valves.
Still another object of the invention is to avoid the difficulties associated with "floatable" disc. A related object is to avoid the difficulties associated with discs that are smaller than their associated seats. Another related object is to avoid the random wear pattern associated with "floatable" discs.
Yet another object of the invention is to reduce disc distortion in check valves. A related object is to reduce the tendency for a disc to be drawn into a flow channel and produce disc distortion.
A yet further object of the invention is to facilitate the seating action of a valve disc and render the valve substantially self purging of debris, such as dirt and dust, that could otherwise interfere with the seating operation.